The present application relates to a connecting piece for a static spray mixer for the mixing and spraying of at least two flowable components in accordance with an embodiment. The present application further relates to the combination of such a connecting piece with a static spray mixer according to an embodiment.
Static mixers for the mixing of at least two flowable components are described, for example, in EP-A-0 749 776 and in EP-A-0 815 929. These very compact mixers provide good mixing results, in particular also for the mixing of high-viscosity materials such as sealing compounds, two-component foams or two-component adhesives, despite a simple, material-saving design of their mixer structure. Such static mixers are usually designed for single use and are frequently used for products which harden such that the mixers can practically no longer be cleaned.
In some applications in which such static mixers are used, it is desirable to spray the two components onto a substrate after their mixing in the static mixer. For this purpose, the mixed components are atomized at the outlet of the mixer by the action of a medium such as air and can then be applied to the desired substrate in the form of a spray jet or spray mist. In particular more highly viscous coating media, e.g. polyurethanes, epoxy resins or similar, can also be processed using this technology.
An apparatus for such applications is disclosed, for example, in U.S. Pat. No. 6,951,310. In this apparatus, a tubular mixer housing is provided which receives the mixing element for the static mixer and which has an external thread at one end onto which a ring-shaped nozzle body is screwed. The nozzle body likewise has an external thread. A conical atomizer element which has a plurality of grooves extending in the longitudinal direction on its cone surface is placed onto the end of the mixing element which projects out of the mixer housing. A cap is pushed over this atomizer element and its inner surface is likewise of conical design so that it contacts the conical surface of the atomizer element. The grooves consequently form flow passages between the atomizer element and the cap. The cap is fixed to the nozzle body together with the atomizer element by means of a retaining nut which is screwed onto the external thread of the nozzle body. The nozzle body has a connection for compressed air. In operation, the compressed air flows out of the nozzle body through the flow passages between the atomizer element and the cap and atomizes the material being discharged from the mixing element.
Even if this apparatus has absolutely proved to be fully functional, its structure is very complex and the installation is complicated and/or expensive so that the apparatus is in particular not very cost-effective with respect to the single use.
Static spray mixers of a much simpler construction are disclosed in the international patent applications PCT/EP2011/057378 and PCT/EP2011/057379 of Sulzer Mixpac AG. In this spray mixer, the mixer housing and the atomizing nozzle are each made in one piece, with the grooves forming the flow passages being provided in the inner surface of the atomizing nozzle or in the outer surface of the mixer housing.